Alkoxylated secondary alcohol sulfates

ABSTRACT

The invention relates to the compounds of formula (I), 
                         
in which R 1  and R 2  represent a linear, branched or cyclic, saturated or unsaturated hydrocarbon group, comprising 1 to 6 carbon atoms, wherein the sum of the carbon atoms of the groups R 1  and R 2  is from 2 to 7; A represents a chain of one or a plurality of units of ethylene oxide, propylene oxide, butylene oxide and mixtures thereof; and n is an integer between 1 and 100 inclusive. The invention also relates to mineral or organic salts thereof; the use of the compounds of formula (I) and/or of one of the salts thereof as a surfactant, a wetting agent, a detergent, an emulsifying agent, a dispersant, a corrosion inhibitor, and the like; and to compositions comprising at least one compound of formula (I) and/or of one of the salts thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is the national phase of International Application No.PCT/FR2018/052763, filed 8 Nov. 2018, which claims priority to FrenchApplication No. 1760597, filed 10 Nov. 2017. The disclosure of each ofthese applications is incorporated herein by reference in its entiretyfor all purposes.

The present invention relates to the general field of alkoxylatedsecondary alcohols which have been subjected to a sulfatation reaction.

The sulfatation of organic alcohols is a well-known route for obtainingorganic alcohol sulfates. Fatty alcohol sulfates are known assurfactants in various applications. Specifically, they have a certainnumber of intrinsic properties in comparison with other cationic andanionic surfactants.

The main intermediary for the synthesis of organic alcohol sulfates isthe organic alcohol itself. Various properties for an alcohol sulfatemay be obtained, depending on the organic alcohol chosen as startingmaterial.

The organic alcohols used for synthesizing these sulfates may be of verydifferent nature, for example: linear or branched, of small or largemolar mass, monofunctional or polyfunctional, inter alia.

They may also be organic alcohols which have undergone an alkoxylationstep, in which one or more units of an alkyl oxide, for example ethyleneoxide, propylene oxide or butylene oxide, have been incorporated intosaid organic alcohol.

The synthesis of organic alcohol sulfates is of real industrialinterest, most particularly when this synthesis is simple andinexpensive to perform, notably starting with available startingmaterials that are readily modifiable to obtain various properties.

In addition, at a time when the environmental challenges are truly high,it is entirely interesting to envisage using a biobased or biodegradablereagent having a good ecotoxicological profile.

Secondary alcohol alkoxylates are a family of compounds which offer awide range of properties. Indeed, the applications are manifold. Theymay notably be used as solvents, as hydrotropes or even as nonionicsurfactants. They may also act as starting material to other compounds,such as etheramines or anionic surfactants obtained by phosphatation orsulfatation. Thus, secondary alcohol alkoxylates constitute a class ofcompounds that are of major industrial interest for many players.

Secondary alcohol alkoxylates are conventionally synthesized by means ofbasic catalysis, for example using potassium hydroxide. Another type ofcatalyst may also be used: the catalyst of dimetallic cyanide type,commonly known as a DMC catalyst. Various documents mention thealkoxylation of various compounds, including alcohols, by basiccatalysis and/or by DMC catalysis.

Thus, a secondary alcohol sulfate is sought, said alcohol beingshort-chained and alkoxylated, the alkoxylation of which is performedvia a simple process that allows low-cost industrial and commercialdevelopment. It would also be advantageous to develop a process forpreparing these sulfates using alkoxylated secondary alcohols, thestarting compound of which is a biobased and biodegradable reagent.

One object of the present invention is to propose a solution forresolving the problems mentioned above.

One subject of the present invention is the compounds of formula (I)below:

in which:

-   -   the groups R₁ and R₂, which may be identical or different,        represent, independently of each other, a linear, branched or        cyclic, saturated or unsaturated hydrocarbon-based group,        comprising from 1 to 6 carbon atoms, it being understood that        the sum of the carbon atoms of the groups R₁ and R₂ ranges from        2 to 7, R₁ and R₂ possibly forming, together with the carbon        atom that bears them, a 6-, 7- or 8-membered ring,    -   A represents a sequence of one or more units chosen from        ethylene oxide, propylene oxide and butylene oxide units, and        mixtures thereof, and    -   n is an integer between, limits inclusive, 1 and 100, preferably        between 2 and 100, more preferably between 3 and 100, more        particularly between 5 and 100 and very preferably between 10        and 100.

A subject of the present invention is also the salts of the compounds offormula (I) above with one or more cationic groups bearing at least onecation chosen from an ammonium cation, a metal cation, a nitrogencation, a boron cation and a phosphorus cation.

Examples of these salts may be described by formula (II) below:

in which:

-   -   M^(x+) represents a cationic group bearing at least one cation        chosen from an ammonium cation, a metal cation, a nitrogen        cation, a boron cation and a phosphorus cation,    -   x is an integer ranging from 1 to 7, and    -   R₁, R₂, A and n are as defined previously.

A subject of the present invention is also the use of at least onecompound of formula (I) and of at least one compound of formula (II). Inthe rest of the present description, and unless otherwise mentioned, theterm “compound of formula (I)” denotes at least one compound of formula(I) or at least one salt thereof of formula (II) or a mixture of atleast one compound of formula (I) with at least one salt thereof offormula (II).

Another subject of the invention is the use of the compound of formula(I) according to the invention, as surfactant, low-foaming surfactant,wetting agent, foaming agent, hydrotrope, detergent, solvent, reactivesolvent, coalescer, compatibilizer, emulsifying agent, dispersant,chemical intermediary, corrosion inhibitor, demulcent, plasticizer,sequestrant, mineral deposition inhibitor, ionic liquid, stabilizer,lubricant, bitumen additive, deinking additive, oil gellant, oreflotation collector, processing aid in the manufacture of plastics,antistatic agent, fertilizer coating additive, for plant protection, fortreating textiles and for enhanced oil recovery, for the production ofelectrodes and electrolytes for batteries.

Other advantages and features of the invention will emerge more clearlyapparent on examining the detailed description. It is specified that theexpression “from . . . to . . . ” used in the present description shouldbe understood as including each of the limits mentioned.

For the purposes of the present invention, the term “ethylene oxideunit” refers to the unit derived from ethylene oxide after opening ofthe oxirane ring. Similarly, the term “propylene oxide unit” refers tothe unit derived from propylene oxide after opening of the oxirane ring.Similarly also, the term “butylene oxide unit” refers to the unitderived from butylene oxide after opening of the oxirane ring.

The compound according to the invention is a compound of formula (I) asmentioned above or a salt thereof of formula (II) as mentioned above.

In other words, the groups R₁ and R₂, with the carbon atom to which theyare attached, denote a secondary radical comprising from 3 to 8 carbonatoms, preferably from 6 to 8 carbon atoms.

Preferably, the radicals R₁ and R₂, which may be identical or different,represent, independently of each other, methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl or hexyl radicals.

Preferably, the radical formed by R₁, R₂ and the carbon atom to which R₁and R₂ are attached is chosen from the 2-octyl radical and the4-methyl-2-pentyl radical. More particularly, the radical formed by R₁,R₂ and the carbon atom to which R₁ and R₂ are attached is the 2-octylradical.

Advantageously, n is between, limits inclusive, 1 and 75, preferablybetween 2 and 75, more preferably between 3 and 75, more particularlybetween 5 and 75 and very preferably between 10 and 75.

Advantageously, n is between, limits inclusive, 1 and 50, preferablybetween 2 and 50, more preferably between 3 and 50, more particularlybetween 5 and 50 and very preferably between 10 and 50.

Advantageously, n is between, limits inclusive, 1 and 30, preferablybetween 2 and 30, more preferably between 3 and 30, more particularlybetween 5 and 30 and very preferably between 10 and 30.

Preferably, n ranges from 2 to 30.

As indicated previously, A represents a sequence of one or more unitschosen from ethylene oxide, propylene oxide and butylene oxide units,and mixtures thereof. According to a particular embodiment, when thecompound of formula (I) includes a mixture of said different units, theymay be distributed randomly, alternately or in blocks.

According to a preferred embodiment, A represents a sequence of at leastone ethylene oxide unit and of at least one propylene oxide unit,distributed alternately, randomly or in blocks.

According to yet another preferred embodiment, A represents a sequenceof at least one ethylene oxide unit and of at least one butylene oxideunit, distributed alternately, randomly or in blocks.

According to yet another preferred embodiment, A represents a sequenceof at least one propylene oxide unit and of at least one butylene oxideunit, distributed alternately, randomly or in blocks.

According to a preferred embodiment of the invention, the group formedby R₁, R₂ and the carbon atom to which R₁ and R₂ are attached representsthe 2-octyl radical, n ranges from 3 to 15, and A represents a sequenceof one or more units chosen from ethylene oxide, propylene oxide andbutylene oxide units, and mixtures thereof.

The invention also relates to mixtures of the mixtures of secondaryalcohol sulfates according to formula (I) as defined above.

A subject of the invention is also the salts of the compounds of formula(I) as defined above.

More precisely, a subject of the invention is the compound of formula(I) in the form of a salt with an alkali metal cation, andalkaline-earth metal cation, a metal cation or with an organic compound,including organic bases.

As indicated previously, these salts may be addition salts of a compoundof formula (I) with an organic or mineral base.

These salts may be salts of organic amines, said amines possiblycontaining one or two or several amine groups. The amines that may beused for salifying the compounds of formula (I) as defined previouslyare preferably chosen, in a nonlimiting manner, from alkylamines,cycloalkylamines, aromatic amines and alkanolamines, said aminespossibly being primary, secondary or tertiary, and also possibly beingalkoxylated.

The compounds of formula (I) may also be salts of heterocyclic amines orof urea. The salts of the compounds of formula (I) with the ammoniumcation (NH₄ ⁺) also form part of the invention.

These salts may be inorganic salts. Advantageously, they are the saltsof the compounds of formula (I) with the elements from column 1 of thePeriodic Table of the Elements (alkali metals), for instance lithium,sodium, potassium, rubidium and cesium.

According to another advantageous embodiment of the present invention,the salts of the compounds of formula (I) with the elements from column2 of the Periodic Table of the Elements (alkali metals), for instancemagnesium and calcium.

According to yet another advantageous embodiment of the presentinvention, the salts of the compounds of formula (I) are the salts withthe elements from columns 3 to 13 of the Periodic Table of the Elements(transition metals), for example vanadium, manganese, cobalt, zirconium,yttrium, iron, cadmium, aluminum and zinc.

Still according to another advantageous embodiment of the presentinvention, the salts of the compounds of formula (I) are those with rareearths (lanthanides and actinides), for instance lanthanum, cerium,thorium, uranium and plutonium.

The compound of formula (I) according to the present invention may beadvantageously obtained by sulfatation of an alkoxylated secondaryalcohol, according to the methods that are well known to those skilledin the art. For example, the sulfatation consists in reacting thesecondary alcohol with a sulfate-based compound chosen from sulfurtrioxide, sulfuric acid, oleum, sulfur trioxide, sulfur trioxidecomplexes, sulfamic acid and chlorosulfonic acid, inter alia.

As indicated previously, the synthesis of these sulfates and thefeatures of their processes for preparing same are known to thoseskilled in the art and are described, for example, by X. Domingo inAnionic Surfactants, volume 5, H. W. Stache, (1996), pages 224-279,Encyclopedia of Chemical Technology, Kirk Othmer, 4^(th) edition,(1997), volume 23, pages 146-175; Ullmann's Encyclopedia of IndustrialChemistry, 5^(th) edition, Elvers, B., Hawkins, S., Schulz, G., (1994),volume A25, pages 778-783.

Preferably, the secondary alcohol used for synthesizing the compound offormula (I) is chosen from 2-octanol and methylisobutylcarbinol;preferably, the secondary alcohol is 2-octanol.

This alcohol is of particular interest in several respects.Specifically, it is a biobased, biodegradable product and has a goodecotoxicological profile. In addition, the boiling point of 2-octanol ishigh and its cost price is entirely reasonable.

According to a preferred embodiment, the alkoxylation of the secondaryalcohol used for synthesizing the compound of formula (I) is obtained bymeans of a catalyst of dimetallic cyanide type, known as a DMC catalyst.Preferably, the catalyst of dimetallic cyanide type may be of any natureknown to a person skilled in the art. This catalyst is notably describedin U.S. Pat. Nos. 6,429,342, 6,977,236 and PL 398 518. Moreparticularly, the catalyst used is zinc hexacyanocobaltate, which issold, for example, by the company Bayer under the name Arcol® or by thecompany Mexeo under the name MEO-DMC®.

Another subject of the invention is the use of the compound of formula(I) according to the invention defined previously, and/or a saltthereof, alone or as a mixture, as surfactant, low-foaming surfactant,wetting agent, foaming agent, hydrotrope, detergent, solvent, reactivesolvent, coalescer, compatibilizer, emulsifying agent, dispersant,chemical intermediary, corrosion inhibitor, demulcent, plasticizer,sequestrant, mineral deposition inhibitor, ionic liquid, stabilizer,lubricant, bitumen additive, deinking additive, oil gellant, oreflotation collector, processing aid in the manufacture of plastics,antistatic agent, fertilizer coating additive, for plant protection, fortreating textiles and for enhanced oil recovery, for the production ofelectrodes and electrolytes for batteries, to mention but a fewapplications among the most common ones known for this type of compound.

According to yet another subject, the present invention relates to acomposition comprising at least one compound of formula (I) as definedpreviously, and/or a salt thereof, alone or as a mixture, with one ormore aqueous, organic or aqueous-organic solvents, for instance water,alcohols, glycols, polyols, mineral oils, plant oils, and the like,alone or as mixtures of two or more thereof, in all proportions.

The composition according to the invention may also contain one or moreadditives and fillers that are well known to those skilled in the art,for instance, in a nonlimiting manner, anionic, cationic, amphoteric ornonionic surfactants, rheology modifiers, demulcents,deposition-inhibiting agents, antifoams, dispersants, pH control agents,colorants, antioxidants, preserving agents, corrosion inhibitors,biocides, and other additives, for instance sulfur, boron, nitrogen orphosphate products, and the like. The nature and amount of the additivesand fillers may vary within wide proportions depending on the nature ofthe intended application and may readily be adapted by a person skilledin the art.

The invention is now illustrated by the examples that follow, which arenot in any way limiting.

EXAMPLES

The 2-octanol (CAS RN 123-96-6) used is the “refined” grade 2-octanolOleris® (purity >99%), sold by Arkema France.

Example 1 Synthesis of Propoxylated 2-Octanol Sulfate Step 1a:Propoxylation of 2-Octanol

591 g (4.54 mol) of 2-octanol dried to less than 200 ppm of water and0.06 g (100 ppm) of catalyst DMC Arcol® are placed in a clean, dry 4 Lautoclave. The reactor is closed and purged with nitrogen and theleaktightness under pressure is checked. The reactor is pressurized withnitrogen to 0.225 MPa at 27° C.

The reaction medium is brought to 90° C. with stirring, and thetemperature is then increased to 120° C. At this temperature of 120° C.,40 g of propylene oxide are introduced. When initiation of the reactionis observed, the rest of the propylene oxide is introduced, i.e. 792 g(13.62 M) in total over a period of 60 minutes at a temperature of 140°C.-150° C. At the end of the addition, the temperature is maintained for30 minutes and the residual propylene oxide is then removed by flushing(stripping) with nitrogen. The reactor is cooled to 60° C. and 1381 g ofalkoxylated 2-octanol comprising 3 propylene oxide units (3 PO) arewithdrawn.

Step 1b: Sulfatation of Propoxylated 2-Octanol

The 2-octanol propoxylated with 3 PO (304 g; 1 M) obtained in Step 1aabove are placed in a stirred 500 cm³ reactor equipped with a stirrer, asolids-addition funnel and under an inert atmosphere of nitrogen. Thesystem is brought to 110° C. with stirring and sparging with nitrogen.The water content, which must be below 2500 ppm, is checked by assaying.The temperature is then brought to 130° C. and the introduction ofsulfamic acid (101.5 g; 1.05 M) is commenced. The rate of introductionis controlled to maintain a temperature of 130° C. The system is thenleft stirring for 1 hour at 130° C.

It is then cooled to 70° C. 0.05 M aqueous ammonia solution is thenadded dropwise so as to neutralize the excess sulfamic acid. The systemis then emptied into a flask. 390 g of product are recovered.

The reaction is represented schematically below:

Example 2 Ethoxylated 2-Octanol Sulfate Step 2a: Ethoxylation of2-Octanol

619 g (4.76 M) of 2-octanol dried to less than 200 ppm of water and 0.06g (100 ppm) of catalyst DMC Arcol® are placed in a clean, dry 4 Lautoclave. The reactor is closed and purged with nitrogen and theleaktightness under pressure is checked. The reactor is pressurized withnitrogen to 0.269 MPa at 20° C.

The reaction medium is brought to 120° C. with stirring. At thistemperature of 120° C., 40 g of ethylene oxide are introduced. Wheninitiation of the reaction is observed, the rest of the ethylene oxideis introduced, i.e. 628 g (14.27 M) in total over 60 minutes at atemperature of 140° C.-150° C. At the end of the addition, thetemperature is maintained for 30 minutes and the residual ethylene oxideis then stripped out with nitrogen. The reactor is cooled to 60° C. and1240 g of alkoxylated 2-octanol comprising 3 ethylene oxide units arewithdrawn. (OHN: 210 mg of KOH/g and coloration of 26 Hz).

Step 2b: Sulfatation of Ethoxylated 2-Octanol

262 g (1 M) of ethoxylated 2-octanol obtained in Step 2a are placed in a500 cm³ reactor, under an inert atmosphere, and 116 g (1 M) ofchlorosulfonic acid are then added dropwise with stirring. The additionof the chlorosulfonic acid is performed while controlling thetemperature, which must not exceed 30° C. At the end of the addition,the temperature of the reactor is maintained at 30° C. for 20 minuteswith stirring. The hydrochloric acid is removed continuously by spargingnitrogen into the reaction medium.

The reaction is monitored by means of the amount of hydrochloric acidproduced. The reaction is considered to be complete when the values nolonger change. 340 g of alkoxylated 2-octanol sulfate comprising 3ethylene oxide units (3 EO) are recovered.

The reaction is represented schematically below:

Example 3 Salification with Sodium Hydroxide

342 g (1 M) of ethoxylated 2-octanol sulfate obtained as describedpreviously (example 4) are placed in a 1 L reactor. 80 g (2 M) of sodiumhydroxide are then added with stirring. At the end of the addition, thetemperature of the reactor is maintained at 60° C. for 15 minutes withstirring. The reactor is then cooled and the product is isolated.

About 380 g of the sodium salt of the alkoxylated 2-octanol sulfatecomprising 3 ethylene oxide units are recovered.

Example 4 Salification with a Fatty Amine

342 g (1 M) of the ethoxylated 2-octanol sulfate obtained in example 2as described previously are placed in a 1 L reactor. The reactor isheated to 80° C. and 259 g (1 M) of a fatty amine bearing a chain ofabout 18 carbon atoms, sold by Arkema France under the name Noram SH®,are then added with stirring while controlling the temperature, whichmust not exceed 80° C. At the end of the addition, the temperature ofthe reactor is maintained at 80° C. for 15 minutes with stirring. Thereactor is then cooled and the synthesized product is recovered.

About 600 g of the fatty amine salt of the alkoxylated 2-octanol sulfatecomprising 3 ethylene oxide units are thus recovered.

The invention claimed is:
 1. A compound of formula (I) below:

wherein: R₁ and R₂ , together with the carbon atom that bears R₁ and R₂forms a 2-octyl radical; A represents a sequence of one or more unitschosen from ethylene oxide, propylene oxide and butylene oxide units,and mixtures thereof; and n is an integer between, limits inclusive, 1and
 100. 2. The compound as claimed in claim 1, in the form of a saltwith an alkali metal cation, and alkaline-earth metal cation, a metalcation or with an organic compound.
 3. The compound as claimed in claim1, wherein n is between, limits inclusive, 1 and
 75. 4. The compound asclaimed in claim 1, wherein n is between, limits inclusive, 1 and
 50. 5.The compound as claimed in claim 1, wherein n ranges from 3 to
 15. 6. Asalt of the compound as claimed in claim 1, corresponding to formula(II) below:

wherein: M^(x+) represents a cationic group bearing at least one cationchosen from an ammonium cation, a metal cation, a nitrogen cation, aboron cation and a phosphorus cation, and x is an integer ranging from 1to 7.